JP2007292470A - Angular velocity sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an angular velocity sensor for reducing the length of a mounting part. <P>SOLUTION: The angular velocity sensor is equipped with first and second tuning-fork vibrators 10a and 10b each comprising a base part and a plurality of arm parts extending from the base part, and the mounting part 30 for thereon mounting the first and second tuning-fork vibrators. The sensor is characterized in that ends of the arm parts of the tuning-fork vibrator 10a confront a side face of the tuning-fork vibrator 10b while a first wire 42a connecting the tuning-fork vibrator 10a to the mounting part 30 is led out in the width direction of the tuning-fork vibrators 10a. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an angular velocity sensor, and more particularly to an angular velocity sensor having a plurality of tuning fork vibrators.

The angular velocity sensor is a sensor that detects an angular velocity at the time of rotation, and is used in systems such as camera shake prevention and car navigation, automobile and robot attitude control systems. Patent Document 1 discloses an angular velocity sensor provided with a plurality of cylindrical vibrators. Patent Document 2 discloses a multi-axis detection angular velocity sensor in which a cylindrical vibrator is supported at two points on a holder. A columnar or rod-shaped vibrator is called a sound piece type vibrator. Patent Document 3 discloses a tuning fork vibrator having a base portion and a plurality of arm portions extending from the base portion.
JP-A-9-292229 Japanese Patent No. 3418245 International Publication No. WO03 / 100350 Pamphlet

  The sound piece type vibrator balances vibrations against external vibrations and cannot cancel the vibrations. Therefore, as in Patent Document 1 and Patent Document 2, when two sound piece type vibrators are arranged in one package, unnecessary vibrations (leakage vibrations) of the sound piece type vibrators caused by external vibrations are mutually Interference (interference noise) degrades angular velocity detection accuracy. Further, the sound piece type vibrator has a narrow immovable area at the natural vibration frequency. For this reason, if each sound piece type transducer is supported except for the non-moving area, the driving vibration of one sound piece type transducer propagates to the other sound piece type transducer and interference noise is generated. The angular velocity detection accuracy deteriorates. Furthermore, since the entire sound piece type vibrator vibrates, it is necessary to support it at two locations. For this reason, it is difficult to maintain the positional accuracy and balance of the two support portions.

  On the other hand, the tuning fork vibrator has a structure in which vibrations from outside are canceled by the left and right arm portions. For this reason, in an angular velocity sensor using a plurality of tuning fork vibrators, it is possible to suppress deterioration in angular velocity detection accuracy and interference noise. However, the tuning fork type vibrator is composed of an arm part and a base part, and an electric signal is input / output from the base part. Since the angular velocity sensor has a plurality of such tuning fork vibrators, the mounting area is increased. Therefore, there is a demand for miniaturization of an angular velocity sensor having a plurality of tuning fork vibrators. In particular, it is required to reduce the long side of the mounting portion of the angular velocity sensor.

  The present invention has been made in view of the above problems, and an object thereof is to provide an angular velocity sensor capable of reducing the long side of the mounting portion.

  The present invention includes first and second tuning fork vibrators each having a base part and a plurality of arm parts extending from the base part, and a mounting part for mounting the first and second tuning fork vibrators. The tip of the arm portion of the first tuning fork vibrator faces the side surface of the second tuning fork vibrator, and the first wire connecting the first tuning fork vibrator and the mounting portion is the The angular velocity sensor is drawn in the width direction of the first tuning fork vibrator. According to the present invention, it is possible to reduce the size of the mounting portion in the longitudinal direction of the first tuning-fork type vibrator that is required to be reduced.

  The said structure WHEREIN: The said 1st wire can be set as the structure pulled out inside the said mounting part. According to this configuration, since the base part of the first tuning fork type vibrator and the base part of the second tuning fork type vibrator can be separated from each other, the vibration interference of the tuning fork type vibrator can be further suppressed.

  The said structure WHEREIN: The 2nd wire which connects the said 2nd tuning fork type vibrator and the said mounting part can be set as the structure pulled out to the longitudinal direction of the said 2nd tuning fork type vibrator.

  The said structure WHEREIN: The 2nd wire which connects the said 2nd tuning fork type vibrator and the said mounting part can be set as the structure pulled out in the width direction of the said 2nd tuning fork type vibrator. According to this configuration, the dimension of the mounting portion in the width direction of the first tuning fork vibrator can be reduced.

  The said structure WHEREIN: A said 2nd wire can be set as the structure pulled out inside the said mounting part. According to this configuration, since the base part of the first tuning fork type vibrator and the base part of the second tuning fork type vibrator can be separated from each other, the vibration interference of the tuning fork type vibrator can be further suppressed.

  The said structure WHEREIN: It can be set as the structure which comprises the sound absorption part for absorbing the vibration of the said 1st and 2nd tuning fork type vibrator provided in the said mounting part. According to this configuration, it is possible to reduce interference noise between the first and second tuning fork vibrators.

  In the above configuration, the sound absorbing portion may be a joining member that joins a control circuit for controlling the first and second tuning fork vibrators to the mounting portion. According to this configuration, it is not necessary to newly provide a sound absorbing part, and the mounting area can be reduced.

  ADVANTAGE OF THE INVENTION According to this invention, the angular velocity sensor which can reduce the long side of a mounting part can be provided.

  Embodiments of the present invention will be described below with reference to the drawings.

  Example 1 is an example of an angular velocity sensor in which two tuning fork vibrators are mounted on a package which is a mounting part. 1A and 1B are perspective views of the angular velocity sensor according to the first embodiment. FIG. 2A is a top view (a cap is not shown), and FIG. 2B is a perspective view of a tuning fork vibrator 10 and a support portion 20. It is. Referring to FIGS. 1 and 2 (a), a first tuning fork type vibrator 10a and a second tuning fork type vibrator 10b having two arm portions are fixed to a cavity type package 30 via support portions 20a and 20b. Has been implemented. The first and second tuning-fork type vibrators 10a and 10b are orthogonal to each other, and each of the longitudinal directions (directions of the arm portions) is set as a detection axis, and an angular velocity about the detection axis is detected. For example, a control circuit 46 in which electronic components are mounted on a substrate is mounted on the package 30. The control circuit 46 is a circuit for controlling the tuning fork vibrators 10a and 10b, supplies a drive signal to the tuning fork vibrators 10a and 10b, and receives detection signals from the tuning fork vibrators 10a and 10b. The package 30 is covered with a cap 40.

  Referring to FIG. 2B, the tuning fork vibrator 10 which is the first tuning fork vibrator 10 a and the second tuning fork vibrator 10 b includes a base portion 13 and two (a plurality of) arm portions extending from the base portion 13. 11 and 12. The support 20 for supporting the tuning fork vibrator 10 has a support surface 22 for supporting the tuning fork vibrator 10 and a mounting surface 24 for mounting on the package 30. The tuning fork vibrator 10 is fixed to the support surface 22 by a joining member such as an adhesive. The mounting surface 24 of the support portion 20 is fixed to the package 30 with a bonding member such as an adhesive. For example, an adhesive such as an epoxy resin can be used as the adhesive. In addition to the adhesive, for example, low melting point glass, solder such as lead-free solder or Au—Sn solder can be used as the bonding member.

FIG. 3A and FIG. 3B are diagrams showing electrode patterns of the tuning fork vibrator 10. The tuning fork vibrator 10 is made of a piezoelectric material such as LiNbO ₃ (lithium niobate) or LiTaO ₃ (lithium tantalate). For example, when LiNbO ₃ (lithium niobate) or LiTaO ₃ (lithium tantalate) is used, a high k23 electromechanical coupling coefficient can be obtained by using a 130 ° to 140 ° Y plate. An electrode using a metal film such as Au, Al, or Cu is formed on the surface of the tuning fork vibrator 10.

  3A shows the front side of the tuning fork vibrator 10, and FIG. 3B shows the back side. The arm part 11 is provided with detection electrodes 11a, 11b, and 11c. The detection electrodes 11a and 11b are connected by an electrode 11d. The detection electrode 11a is provided with an extraction electrode 11f. The electrode 11c is connected to the extraction electrode 11e. Similarly, the arm part 12 is provided with detection electrodes 12a, 12b, and 12c. The detection electrodes 12a and 12b are connected by an electrode 12d. The electrode 12a is provided with a lead electrode 12f. The electrode 12c is connected to the extraction electrode 12e. A driving electrode 14a is provided on the surface of the tuning fork vibrator 10, and is connected to the extraction electrode 14b. Similarly, a drive electrode 15a is provided on the back surface and connected to the extraction electrode 15b.

  FIG. 4A and FIG. 4B are diagrams for explaining the drive mode and the detection mode of the tuning fork vibrator 10. Referring to FIG. 4A, a vibration mode is generated in which the arm portions 11 and 12 are opened and closed by applying a drive signal to the drive electrodes 14a and 15a of the tuning fork vibrator 10. This vibration is a vibration parallel to the surfaces of the arm portions 11 and 12, and this is called an in-plane vibration mode. Here, when an angular velocity is applied to the detection axis, a vibration mode in which the arm portions 11 and 12 vibrate back and forth as shown in FIG. 4B appears due to Coriolis force. This vibration is a twist vibration perpendicular to the surfaces in the directions of the arm portions 11 and 12, and this is referred to as a surface vertical vibration mode. By detecting this vibration mode by the detection electrodes 11a to 11c and 12a to 12c, the angular velocity around the detection axis can be detected. The vibration mode used for driving is called a drive mode, and the vibration mode used for detection is called a detection mode. The drive mode and detection mode are not limited to the vibration modes shown in FIGS. 4 (a) and 4 (b). The detection mode only has to appear by the Coriolis force with respect to the drive mode. In each vibration mode, a region that does not vibrate is called a node. In FIG. 4A, the symmetry plane of the tuning fork vibrator 10 is a node A. In FIG. 4B, the central axis of the tuning fork vibrator 10 is the node B.

  5 (a) and 5 (b) show a wire 42a that connects the first tuning-fork type vibrator 10a and the second tuning-fork type vibrator 10b of the comparative example and Example 1 and the pads 44a and 44b of the package 30, respectively. It is the figure which showed 42b. Referring to FIG. 5A, in the comparative example, the tip of the first tuning fork type vibrator 10a (tip of the arm part) faces the side surface of the arm part of the second tuning fork type vibrator 10b. The pad 44a of the package 30 is provided behind (that is, the direction of the base portion) in the longitudinal direction (that is, the direction in which the arm portion extends) of the first tuning fork type vibrator 10a. Therefore, the first wire 42a connecting the first tuning fork vibrator 10a and the pad 44a is drawn out in the longitudinal direction of the first tuning fork vibrator 10a. Although not shown in FIG. 5A, the first wire 42a is connected to the extraction electrodes 11e, 11f, 12e, 12f and 14b shown in FIG. 3A of the first tuning fork vibrator 10a, respectively. Similarly, the second wire 42b that connects the second tuning-fork type vibrator 10b and the pad 44b of the package 30 is drawn out rearward in the longitudinal direction of the second tuning-fork type vibrator 10b.

  Referring to FIG. 5B, in the first embodiment, the pad 44a is provided in the width direction of the first tuning fork type vibrator 10a as compared with the comparative example, and the first tuning fork type vibrator 10a and the pad 44a Are pulled out on both sides in the width direction of the first tuning fork vibrator 10a. Similar to the first comparative example, the second wire 42b connecting the second tuning fork vibrator 10b and the pad 44b is drawn out in the longitudinal direction of the second tuning fork vibrator 10b.

  In an angular velocity sensor provided with two tuning fork vibrators 10, the detection axes of the two tuning fork vibrators 10 are substantially orthogonal. In this case, the smallest mounting area is the case where the tip of the first tuning fork type vibrator 10a is arranged so as to face the side surface of the second tuning fork type vibrator 10b as shown in FIG. . In this case, the package dimension L1 in the longitudinal direction of the first tuning fork type vibrator 10a needs to be larger than the sum of the length La of the first tuning fork type vibrator 10a and the width Wa of the second tuning fork type vibrator 10b. . On the other hand, the package dimension L2 in the width direction of the first tuning fork vibrator 10a needs to be larger than the length Lb of the second tuning fork vibrator 10b. Thus, the dimension L1 of the package 30 is longer than L2.

  The tuning fork vibrator 10 is divided into an arm portion 11 and 12 mainly having a function of vibrating and a base portion 13 having a function of holding the arm portions 11 and 12 and being held by the package 30 due to its structure. Therefore, it is preferable that the base portions 13 of the two tuning fork vibrators 10 are separated and supported by the package 30. This is because the vibrations of the two tuning fork vibrators 10 interfere when the base portion 13 is supported in close proximity. Therefore, it is preferable to dispose the tip of the arm part of the first tuning fork type vibrator 10a so as to face the side surface of the arm part of the second tuning fork type vibrator 10b. Thereby, since the base part 13 is mounted apart, it is possible to reduce interference of vibrations of the two tuning fork vibrators 10.

  In the tuning fork vibrator 10, a wire connecting the tuning fork vibrator 10 and the package 30 is also drawn from the base portion 13. Further, the base portions 13 of the two tuning fork vibrators 10 are mounted apart. Under such circumstances, as in the comparative example of FIG. 5A, the first wire 42a and the second wire 42b are arranged in the longitudinal direction of the first tuning fork vibrator 10a and the second tuning fork vibrator 10b, respectively. , The pads 44a and 44b are required behind the first tuning fork vibrator 10a and the second tuning fork vibrator 10b, respectively. Therefore, the dimensions Lp of the pads 42a and 42b are further required as the dimensions L1 and L2 of the package 30.

  As described above, since the dimension L1 of the package 30 is longer than L2, it is particularly required to reduce L1. According to the first embodiment, the first wire 42a is drawn out in the width direction of the first tuning fork type vibrator 10a. Thereby, it is not necessary to arrange the pad 44a behind the first tuning fork vibrator 10a, and the dimension L1 of the package 30 can be reduced by the dimension Lp of the pad 44a.

  As shown in FIGS. 6A and 6B, the first wire 42a is in the width direction of the first tuning-fork type vibrator 10a and can be pulled out to the outside and the inside of the package 30. However, it is preferable to pull out the first wire 42 a to the inside of the package 30. Thereby, since the base part of the 1st tuning fork type vibrator 10a and the base part of the 2nd tuning fork type vibrator 10b can be separated, interference of vibration of a tuning fork type vibrator can be controlled more.

  As shown in FIG. 5B, the second wire 42b may be pulled out in the longitudinal direction of the second tuning-fork type vibrator 10b. However, as shown in FIG. The tuning fork vibrator 10b is preferably drawn out in the width direction. Thereby, the dimension L2 of the package 30 can be reduced by the dimension Lp of the pad 44b. Furthermore, it is preferable that the second wire 42 b is pulled out to the inside of the package 30. Thereby, since the base part of the 1st tuning fork type vibrator 10a and the base part of the 2nd tuning fork type vibrator 10b can be separated, interference of vibration of a tuning fork type vibrator can be controlled more. It should be noted that here, the drawing of the wire in the longitudinal direction and the width direction of the tuning fork vibrator 10 means that the wire is pulled out so as to be connected to, for example, the pad 44 provided in the longitudinal direction and the width direction of the tuning fork vibrator. It is.

  The second embodiment is an example in which a sound absorbing portion is provided on a printed circuit board as a mounting portion in addition to the configuration of the first embodiment. Referring to FIGS. 7A and 7B, as in the first embodiment, two orthogonal first tuning fork type vibrator 10a and second tuning fork type vibrator 10b are mounted on printed circuit board 31 as mounting parts. Has been. In FIGS. 7A and 7B, the first wire and the second wire are not shown. Referring to FIG. 7A, a sound absorbing material 32 is provided on the printed circuit board 31 as a sound absorbing portion for absorbing the vibration of the tuning fork vibrator 10a or 10b. The sound absorbing material 32 is a soft material that absorbs vibrations of the printed circuit board 31, and for example, a resin such as an epoxy resin or a silicon resin can be used. With reference to FIG.7 (b), the weight 34 is provided on the sound absorption material 32 as a sound absorption part. Other configurations are the same as those in FIG. The sound absorbing material 32 also has a function as an adhesive for adhering the weight 34. In FIG. 7B, the vibration of the printed circuit board 31 can be more absorbed by the weight. According to the second embodiment, the noise absorption part absorbs the vibration propagating through the printed circuit board 31 from one tuning fork vibrator 10a or 10b to the other tuning fork vibrator 10a or 10b, thereby reducing interference noise. Can do. The sound absorbing portion is preferably disposed between the tuning fork vibrators 10a and 10b in order to absorb vibration from one tuning fork vibrator 10a or 10b to the other tuning fork vibrator 10b or 10a. As the sound absorbing part, vibration may be absorbed by partially increasing the thickness of the mounting part such as the printed circuit board 31 to increase the moment of inertia so that the vibration of the tuning fork vibrator 10a or 10b is difficult to propagate. .

  The third embodiment is an example in which a sound absorbing material is used to hold the control circuit 46. FIG. 8 is a perspective view of the third embodiment. Referring to FIG. 8, the first tuning fork type vibrator 10 a and the second tuning fork type vibrator 10 b are mounted on a cavity type package 30 as a mounting portion, as in the first embodiment. A sound absorbing material 32 similar to that shown in FIG. 7A of the second embodiment is provided on the package 30. A control circuit 46 having the same function as in the first embodiment is mounted on the sound absorbing material 32. The sound absorbing material 32 also has a function as an adhesive for holding the control circuit 46 in the package 30. In the third embodiment, the sound absorbing material 32 (sound absorbing portion) is a joining member that joins the control circuit 46 for controlling the first and second tuning fork vibrators 10 a and 10 b to the package 30. Thereby, it is not necessary to provide a new sound absorbing part, and the mounting area can be reduced.

  As the mounting portion, Example 1 and Example 3 are examples using the package 30, and Example 2 is an example using the printed circuit board 31. However, as long as it has a function of mounting the tuning fork vibrators 10a and 10b, other These members may be used. The first tuning fork type vibrator 10a and the second tuning fork type vibrator 10b have two arm portions 11 and 12, but the arm portion may be a plurality of tuning fork type vibrators.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims. It can be changed.

FIG. 1 is a perspective view of the angular velocity sensor according to the first embodiment. FIG. 2A is a top view of the angular velocity sensor according to the first embodiment, and FIG. 2B is a perspective view of the tuning fork vibrator and the support portion of the angular velocity sensor according to the first embodiment. FIG. 3A and FIG. 3B are diagrams showing electrode patterns on the surface of the tuning fork vibrator. FIG. 4A and FIG. 4B are diagrams showing vibration modes of the tuning fork vibrator. FIG. 5A is a top view of the angular velocity sensor according to the comparative example, and FIG. 5B is a top view of the angular velocity sensor according to the first embodiment. FIGS. 6A to 6C show another example of the angular velocity sensor according to the first embodiment. FIG. 7A and FIG. 7B are perspective views of the angular velocity sensor according to the second embodiment. FIG. 8 is a perspective view of the angular velocity sensor according to the third embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Tuning fork type vibrator 10a First tuning fork type vibrator 10b Second tuning fork type vibrator 11, 12 Arm part 13 Base part 20 Supporting part 30 Package 31 Printed circuit board 32 Sound absorbing material 34 Weight 40 Cap 42a First wire 42b Second wire 44a, 44b Pad 46 Control circuit

Claims (7)

First and second tuning fork vibrators each having a base portion and a plurality of arm portions extending from the base portion;
A mounting portion for mounting the first and second tuning-fork vibrators,
The tip of the arm portion of the first tuning fork vibrator faces the side surface of the second tuning fork vibrator,
An angular velocity sensor, wherein a first wire connecting the first tuning fork vibrator and the mounting portion is drawn in a width direction of the first tuning fork vibrator.   The angular velocity sensor according to claim 1, wherein the first wire is drawn inside the mounting portion.   3. The angular velocity sensor according to claim 1, wherein a second wire connecting the second tuning fork vibrator and the mounting portion is drawn out in a longitudinal direction of the second tuning fork vibrator.   3. The angular velocity sensor according to claim 1, wherein a second wire connecting the second tuning fork vibrator and the mounting portion is drawn in a width direction of the second tuning fork vibrator.   The angular velocity sensor according to claim 4, wherein the second wire is drawn inside the mounting portion.   The angular velocity sensor according to any one of claims 1 to 5, further comprising a sound absorbing portion that is provided in the mounting portion and absorbs vibrations of the first and second tuning fork vibrators. The angular velocity sensor according to claim 6, wherein the sound absorbing part is a joining member that joins a control circuit for controlling the first and second tuning-fork vibrators to the mounting part.

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